The way I interpret the RAW of True Grit(Cheat Death) is...
The first lethal blow costs all but one of your grit, reduced by one from all your grit.
The non-reduced cost is now one grit, so with the reduction you can continue to Cheat Death as long as you have at least 1 grit point.
If you lose that last grit point, Cheat Death stops functioning.


A somewhat weaker version with stronger RAW assumptions uses the Run Like Hell Dare. Run Like Hell automatically gives Grit whenever you run out of Grit while 100+ feet from the nearest enemy, so you always have at least one grit for Cheat Death while out of combat or whenever you manage to position yourself far enough away from it.